我有以下查询需要从 Oracle 移植到 MySQL。它在两者中执行时都没有任何编译错误，但结果表不同。在 Oracle 中，我得到每个计数列下的单个计数。但是在 MySQL 中，无论计数应该在哪里，它们都落在 a5 以下。像这样：
在甲骨文中：
但在 MySQL 中：
select x1.alert_level, count(x1.a1), count(x1.a2), count(x1.a3),
count(x1.a4), count(x1.a5) from
(select
table_name.column_name alias,
case when (now() - column_name) <= 7 then 1 end as a1,
case when (now() - column_name) between 7 and 30 then 1 end as a2,
case when (now() - column_name) between 30 and 60 then 1 end as a3,
case when (now() - column_name) between 60 and 90 then 1 end as a4,
case when (now() - column_name) >= 90 then 1 end as a5
FROM tables
WHERE filter_conditions) x1 GROUP BY x1.alias;
如何调和差异以使 MySQL 输出看起来像 Oracle 输出？感谢您的帮助！